All the info is on the disclosure Scotland website. If I recall it goes like this;
Basic disclosure-Shows any unspent convictions.
Standard disclosure-Shows any unspent and spent convictions.
Enhanced Disclosure-As standard disclosure only it gets personally reviewed by a police officer who adds anything else he thinks relevant to the job you are applying for.
The basic you can apply for yourself the other two have to be applied for by the company.
For an airside pass you just need a basic. Cautions don't show up on either the basic or standard one.